Automatic telephone-exchange system.



A. E. LUNDELL.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION AFILED UG.22, 1913.

Patented Jau. 18, 1916.

5 SHEETS-SHEET l.

w www ma nl WE, A@ MT. A,

V//fnessess @2%. l" www 'aimte Jan. I8, i916.

5 SHEETS-SHEET 2.

A. E. LUNDI-ILL.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

l APPLICATION FILED AUC-L22. 1913. www.

Vl/ifnesses;

A. E. LUNDELL.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED AUG.22, l913. 1,916,819, Patented Jan. 18y 1916.

5 SHEETS-SHEET 3.

I/1//7ne ases:

W-Ma

A. E. LUNDELL.

AUTOMATIC TELEPHONE EXCHANGESYSTEM.

APPLICATION FILED AUG.22, T913. v Lll Patented Jan. 18, 1916.

5 SHEETS-SHEET 4.

whe mlf @wwf umn um mmm www //7 l/en/o f.' A/ben E. ande/ A. E. LUNDELL.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED AuG.22, 1913.

5 SHEETS-SHEET 5.

IIIIIIIIIII STATES PATENT @FFME ALBEN E. LUNDELL, F NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, T0 WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

AUTOMATIC TELEPHONE-EXCHANGE SYSTEM.

To all whom it may concern:

Be it known that I, ALBEN E. LUNDELL, a

citizen of the United States, residing at New York city, inthe county and State of New York, have invented a certain new and useful Improvement in Automatic Telephone- Exchange Systems, of which the following is a full, clear, concise, and eXact descrlption.

One of the features of this invention relates' to a telephone exchange system and particularly to the provision of a switching means whereby the operators set is automatically associated with and disassociated from the selected connecting circuit.

Another feature of this invention relates to a signal which by one condition indicates that a call is being established, by another condition that the wanted subscriber is being called and by still a third condition that the called subscriber has answered. This signal will remain in the first condition only a short time if the connection proceeds properly, but if the call does notfproceed properly, the signal will remain in the first condition and indicate trouble tothe operator.

A further feature of this invention involves the provision of a plurality of controllers or senders at an operators position and means for allotting one of said senders to a cord when taken for use and a signal to indicate -to the operator when all the senders are in use.

Still another feature relates to means whereby the sets of pulses transmitted in effecting one stage of the selection are controlled by one sequence switch and the sets y of pulses required for establishing the rest of the connection are controlled by another sequence switch which is required at other times for other purposes.

Another feature relates to means whereby when a connection is knocked down by means of the actuation of the wipe-out key,

signed for use in semi-automaticy systems wherein sending apparatus is located at theA Specification of Letters Patent.

Patented Jan. 18, 1916.

Application led August 22, 1913. Serial No. 786,165.

central oflice and arranged for actuation by an operator in accordance with instructions received from a calling subscriber. In such automatic systems, the initial connection to the calling line may be made by any suitable switchin mechanism, but in the system herein dlsclosed, this'connection is made by the operator inserting a plug at the answering nend of the cord circuit into the jackof the calling line. Each cord terminates at one end in a first selector switch, and sending mechanism is temporarily associated with the cord circuit while the connection is being established, for the purpose of controlling the operation of the first selector and of the succeeding switches (not shown in the present disclosure), by means of which the connection is established.

The feature of the invention, whereby the operators telephone set may be automatically connected to and disconnected from any selected cord or connecting circuit, depends principally on the use of a sequence switch associated with the operators set.

These sequence switches, one of which is' preferably provided for each cord circuit, are automatically controlled to move to listening position to associate the operators telephone with the cord as soon as the cord is connected to a calling line, and to move to non-listening position to remove her telephone from association with such cord when the operator connects a second cord to another calling line, or as soon as the connection has reached the ringing stage. Means are also provided whereby, when the operators set has been disassociated from the firstvcord by the insertion of a plug of a second cord in a jack of another calling line, means will be actuated so that when the connection being established through the first cord reaches the ringing stage, the condition which would be operative to remove the operators set from association with the first cord if still connected thereto, will not be effective to remove the operators set from the second cord. Manually operable keys are also provided whereby the operator may at any time cause the operation of the listening key sequence switch to remove her set fromv a cord or to reassociate her set with 'a cord while the connection is being established. The listening key sequence switch may be caused to return from non-listening position to normal when the connection is disestablished.

Referring now to the drawings, Figures 1, 2, 3, 4 and 5 when placed together with Figs. 2 and 3 below Fig. 1 in the order named, and Figs. 4 and 5 to the vright of Figs. `2 and 3 respectively, form a circuit diagram of a system with which my inven-l tion is adapted to be used.

` SeZectmn--At the right in Fig. 1 is shown a selector switch of the panel type. This switch comprises a longitudinally movable shaft 20 having a plurality of sets 21 of brushes Xed thereto, only one set being shown in the drawings. Each set of brushes is adapted to traverse a section or group of trunk terminals 231. 22 represents a rotatable power drum and 23 is an idler pulley adapted, through the medium of magnet 220, to force the bar 24 into engagement with the power drum 22, whereby the shaft and the brushes carriedthereby are raised. Similarly,- the rotatable power drum 28 is arranged to return the switch to normal. Carried by the shaft 20 is a plurality of interrupter brushes 223, 232 and 240 which,

in the movement of the switch shaft, are adapted to traverse the commutators or interrupters A, B and C respectively. The brushes of each of the sets 21 are normally held from engagement with the trunk terminal contacts by meansof an arm on a bell crank trip lever 25 being positioned between 35' the two innermost brushes of the set.

A trip rod 26 actuated by the magnet 228 is provided. This rod carries a plurality of flexible trip fingers (only one of which is shown) which are positioned at lprogressively increasing distances from the normal position of the horizontal arms of the trip levers 25. Thus, if during the preliminary upward movement of the trunk shaft the rod 26 -is rotated, one of the trip fingers 29 will operatively engage its respectivetrip lever 25, while the remaining trip ngers will pass through the line of travel of their respective trip levers to the other side thereof. The set ofbrushes to be tripped or released, therefore, depends on the distance the shaft-travels and, consequently, on the number of segments of the A commutator ,traversed by the brush 223 before the energization of the trip magnet 228.

Oord finden- The cord finder X, shown l in the upper left corner of Fig. 2 of the drawing, is of the rotary type and comprises five brushes 329 and as many sets of five stationary terminals 331 as there are cord or connecting circuits at an operators position. The brushes are mounted on a carriage adapted to rotate with a haft 353, at the lower end of which is a flexibly mounted disk 354. This disk is adapted to be engaged by a roller 355 mounted on a continuously movable power shaft 356, the

the callotter shown in the dotted inclosure in the upper right corner of Fig. 2. This allotter which-is common to both cord inders is merely a sequence switch structure which, in position 1, renders cord finder X operative and in position 6 finders Z operative.

Sequence swz't0hes.-The controlling circuits associated with the various parts of the exchange system, which must be established in a definite order at successive stages of the operation of the system lto bring the various devices or parts into operation as required, are established by automatic switching mechanisms which are termed sequence switches. There is a sequence switch associated with the operators listening apparatus and one with the first or district selector switch in Fig. 1 of the drawings. Another sequence switch is associated with the cord finder in Fig. 2 of the drawings and still another is associated with a sender or counting relay structure in Fig. 3. Each of these sequence switches consists briefly of a frame wherein is mounted a rotatable shaft having a series of disks of fiber or other insulating material secured thereto. On each side of each insulating disk is a disk or circular plate of conducting material which is cut away or skeletonized so as to provide any desired arrangement of contacts. The two plates associated with each insulating disk are electrically united by their securing/ rivets. The rotatable disks or wipers arerepresented in the drawing as the long contact. A plurality of springs or brushes is provided for lengagement with each pair of conducting disks and by means thereof and by properly cutting away and arranging the plates on the insulating. disk, any two or more brushes arranged for engagement therewith .may be electrically united at any stage of rotation of the shaft. The sequence switch` positions, at which the various springs or brushes are in engagement with the rotatable disk, are indicated by numerals placed adjacent to theseveral contacts respectively. Certain brushes are illustrated in the drawing as 'being in engagement with the rotatable disks, and it is renders cord isc ment. These mechanisms, inthe embodiment herein shown, comprises continuously rotating friction disks 116, 270, 357, 437 and 706 respectively. The rotatable shaft of each sequence switch is provided with a coperating friction disk indicated in the drawings by the same reference characters primed and an electromagnet is provided for causing effective engagement of the friction disks, whereby the switch shaft may be rotated. Each sequence switch is provided with a special contact indicated in the drawings by reference characters ending in each instance in 01. The numerals appearing adjacent to these contacts represent the only positions in which they are open and consequently the only positions at which the sequence switch can stop.

In the drawings, each sequence switch is designated by a different hundreds numeral and all contacts controlled thereby are designated by reference characters having the same hundreds numeral; that is, the listening key sequence switch of Fig. l is designated by the reference numeral 151 and its motor magnet by 100 and all the' sequence switch contacts controlled thereby and which appear in the dotted inclosure at the upper left corner of this sheet of drawings are indicated by one hundreds digits. Correspondingly, all the sequence switch contacts controlled by the selector sequence switch motor magnet 200 appearing in the lower left corner of Fig. 1 are indicated by two hundreds digits. The motor magnet of the cord finder sequence switch, Fig. 2, is designated 300 and its contacts by three hundreds digits. The motor magnet of the sender sequence switch is designated 400 and its contacts by four hundreds digits.

In the drawings appear certain sequence switch contacts which are controlled by sequence switches associated with apparatus not shown herein. contacts will be controlled by sequence switches corresponding in every way to the sequence switch at the position of which they appear in the drawing. Such sequence switch contacts are inclosed by dotted rectangles and are indicated by the same reference character primedas the corresponding contact in the drawings.

In the following description the reference characters of each sequence switch contact will be followed by a numeral in'brackets which will indicate its position at the time a circuit occurs. For illustration, referring to contact 206 a-t the lower left corner of Fig. 1, if a circuit were to be traced from conductor 312, Fig. 2, to a conductor 207, Fig. 1, when the district sequence switch 251 is in position 2, it would be described as: **="*****conductor 812, upper sequence switch contact 206 (2), conductor 207, Where a sequence switch spring In each instance thesej has not upper and lowericontacts closed at the same position, these terms will be omitted.

Keys @mi regieren-The operators key set vand set of registers are shown in Figs. 4 and 5. The various circuits which' determine the selection controlling operations of the operators sender are established by a plurality of recording devices herein termed registers, which take their position in response to the operation of manually operablekeys controlled by an operator upon which the designation of the Qline wanted may be indicated. These keys are designed to be held in their depressed position by means of a locking magnet or magnets, indicated on the drawings at 517, which are adapted to retain the keys of the set in their depressed position until they are denergized. Upon the de'energization of thelocking magnet, the keys of the associated set will be restored to normal position by means not shown but which are usual in apparatus of this kind. Each key when depressed is adapted to close certain contacts in the circuits of the stop relays which are shown in the diagram.

The preferred form of the registers such as are used in connection with my invention and shown diagrammatically in Fig. 4, is substantially the same as that of the sequence switches hereinbefore described with the addition of a stop relay. The sets of contact devices shown above the power magnet are those connected to the operators keys and by which is determined the position in which the register will stop. r1`he sets of contact devices located below the power magnet on Fig. 5 are the ones closed in the, vario-us positions ofthe register to determine the operations of the sender. The registers as well as the sequence switches are provided with special contacts shown in the drawings in each instance immediately vabove the power magnet. These contacts` are open in each of the positions of the register but closed between each two positions thereof. As in the ordinary sequence switch, the contact devices of the register are open in all their positions except those indicated upon the drawings by numerals immediately adjacent the contacts, These register sequence switch structures havev no normal position and after they have performed their function, they remain in their set position until again taken for use in connection with the establishment of another call. Five registers are provided corresponding respectively to the districts of the system, the oi/iices in a district, the hundreds, the tens and the units of the designation of the line wanted. As hereinafter described, when the registers are brought successively in association with the sender or selection controlling apparatus herein shown as counting relays, the contact devices shown below the power magnets of the respective registers will control the operation of such counting the other registers of the group are individual to the corresponding sets of keys. It will, therefore, be apparent that the district and oiiice registers will respond to the clepression of the oiice key to record not only the district in which such ofiice is located, but also the particular office in such district. The numerical registers similarly will respond to the depression of the numerical keys to takeJ up positions corresponding to the depressed keys in their respective associated sets of keys. In each position the disks of the registers will close a certain distinctive.combination of switch contacts whereby the operation of the counting relays may be controlled. The set of keys here shown is common to two sets of registers, the fixed contacts of said keys being connected to corresponding controlling contacts of the registers of both sets. This is indicated in the drawings by the Imultiples from the conductors leading to the controlling contacts. A

The operation of the system very briey is as follows A subscriber in removing his receiverfrom its hook causes a signal lamp to glow. The operator thereupon connects a cord circuit to the terminals of the calling line. The operators listening key sequence switch is then automatically operated to connect the operators listening set to the selected cord and remove it from any other cord to which it may be connected. The

subscriber then informs the operator what connection is wanted, whereupon the operator depresses the appropriate combination of register keys and the connection is automatically established. Vhen the ringing stage is reached, the listening key sequence switch is again automatically operated to remove the operators set from the connection.

The operation of the system will now be described more in detail as, by following the operation, it is thought the invention can be most readily understood.

Upon the subscriber at S removing his receiver from the hook, a circuit is completed from battery 7 through left winding of relay 8, left armature and contact of relay 9, upper side of the subscribers line, substation apparatus, lower side of the subscribers line, contact and right armature of relay 9, right winding of relay 8 and back to battery. Relay.: 8 is energized, completing a circuit for the signal lamp 10 from the live pole of grounded battery 7, through armature and contact of relay 8. Upon lighting of lamp 10, the operator inserts plug 11 in jack 12 of the calling line, completing a cirtact 102 (l), front contact and armature of relay 109 to ground. Listening key sequence switch under the control of its master contact 101 moves to position 5, connecting the operators set to the line through sequence switch contacts 280 and 281. If at this time the operators set is associated with another connecting circuit by the listening key sequence switch at said connecting circuit, this sequence switch will be moved out of position 5, or listening'in position, by a circuit from battery, through the motor. magnet at the other sequence switch, contact 111 (5) (see dotted rectangle, Fig. l), common conductor 104, sequence switch contactl 111 (2 to 4) to ground, thus assuring that the'operators set will be connected to only one cord circuit at a time. Common conductor 104 will extend to contacts 111 at each cord circuit of the operators position. Listening key sequence switch, in moving to position 5, closes a circuit for the motor magnet of the selector sequence switch 251 as follows: from battery 202, motor magnet 200, conductor 203, sequence lswitch contact 204, sequence switch contact 205 (1), sequence switch contact 103 (2-5) to ground. The selector sequence switch` motor magnet is energized and under the control of its special contact 201 goes to position 2. Signal lamp 246 now begins to flash, its'circuit being completed through sequence switch contact 247 (2 to 12) and the contact of interrupter 248. Lamp 246 continues to Hash until the connection is established. Assuming that the allotter is in position 1, a circuit is now completed for the motor magnet 300 of the cord finder sequence switch, from battery 302, magnet 300, conductor 303, sequence switch contact .304 (1), conductor 305, sequence switch contact 206 (2), conductor 207, sequence switch contact 208 to ground. The cord linder sequence switch under the control of its special contact 301 is carried to position 2. The cord finder sequence switch in position 2 completes a circuit from battery 30G, power magnet 307 of the cord finder, sequence switch contact 308 (2), back contact and right armature of test relay 309, to ground. Power magnet 307 is thus energized and the brushes of the cord finder start to hunt. Upon the brushes arriving on the terminals associated with the selected connecting circuit, a circuit will be completed from battery 310, sequence switch contact 311 (2), right winding oftest relay 309, upper brush of the cord linder, upper contact of the terminal set, conductor 312, se uence lswitch contact 206 (2), conductor 20% and sequence switch contactl 208 to ground. Test relay 309 is thereupon energized and interrupts at its right back contact the circuitfor. the power magnet and at its front right contact completes a circuit from battery 306, through stop magnet 313, sequence switch contact 314 to right front contact and armature of relay 309to ground. The cord finder is thus stopped with the brushes in engagement with the terminals associated with the cord circuit. A circuit is also completed from battery 302 through sequence switch motor magnet 300, sequence switch contact 315 (2), right front `contact and armature of testlrelay 309 to ground. The cord finder sequence switch then goes to position 3. On the attraction of the left armature of the test relay, a locking circuit is completed from battery 316, left armature and contact of relay 309, left winding of said relay, the second brush from top of the cord finder, its corresponding contact terminal, conductor 317, sequence switch contact 209 (2), and back contact and armature of knockedown relay 210 to ground.

The operations thus far described result from inserting a plugin the jack of the calling subscribers line. No further operation takes place until the recording keys are depressed.

The operator having ascertained the number of the line wanted, depresses the proper recording keys. These keys are held down in a well-known manner by the magnets 517, the circuit of which was completed' through sequence switch contact 344 (2'to 9) when the cord finder 'sequence switch went to position 2. These keys remain held down until the cord finder sequence switch passes out of position 9 atv the end of the sending operation.

We will assume that the call is for a subv scriber whose district and oliice are 'represented by oiiice key 518 and whose number is 499. Keys 518, 519, 520 and 521 are therefore depressed. Depressing key 518 causesl the district and ofice registers to rotate, the circuits for energizing their clutch magnets 512 and 513 extending through the back contacts of their respective cutoff relays 502 and 504 to lead 503, thence through contact 321v (2 to 4), wire 322 to ground through key 518. The district and oflice registers continue to rotate until a circuit is established for their cutoff lor stop relays, through the depressed office key to ground. The district register will therefore stop in position 2 andv the oiiice register in position 1. The hundreds, tens and units registersfwill also roregisters move to positions 4, 9 and 9 respectively. 9

- As soon as thedistrict reg1ster assumes lts set position, a circuit is completed from battery 302 through cord finder sequence switch motor magnet 300, conductor 318, sequence switch contact 319 (3), conductor 320, front contact and armature of stop relay 502, conductor 503,"sequence switch contact 321 (3), conductor 322 to ground through the oper ated oiice key. The cord finder sequence switch is moved to position 4. A circuit is now completed from battery 211, district line relay 212, conductor 213, sequence switch contact 214 (2), sequence switch contact 215 (2), conductor 323, middle contact of the termlnal set, middle brush of the cord finder, conductor 324, sequence switch contact 325 (4), stepping relay 402,right armature and contact of cut-off relay 403 and sequence switch contact 404 (1) to ground.

The circuit just traced and other similar circuits are known as fundamental circuits. That is, the circuit from the line or controlling relay of a selector through the sender stepping relay is known as a fundamental circuit and will hereinafter be so referred to. A fundamental circuit is used in each selective operation which is controlled by the sender. Line relay 212 is now' energized and a circuit isy completed from battery 202, through sequence switch motor magnet 200, conductor 203, sequence switch contact 204, conductor216, sequence switch Contact 217 (2), conductor 218, front contact and left armature of relay 212, back contact and right armature of relay 210 to ground. The district sequence switch thereupon passes to position 3. In position 3l a circuit is completed from battery 219 through switch power magnet 220, conductor 221, sequence switch contact 222 (3), conductor 218, front contact and left armature of line relay 212,

back contact and right armature of relay 402, a circuit is closed from battery 407 through conductor 408, counting relay 417, back contact and armature of counting relay 418, conductor 411, lower register contact 601 (2), conductor 412, sequence switch contact 413 (1), contact and armature of relay 402 to ground. Relay 417 is thereupon energized and attracts its armature, thus 'com pleting an energizing circuit in series therewith for relay 418 from battery 407 conductor'408, relays 417and 418,A armature and contact of relay 417, sequence "switch contact 419 (l), conductor 420,-ssequence switch contact 314 (4) to ground at right armature of relay 309. Relays 418 and 417 are thereupon locked up. The energization of relay 418includes the relay`438 in the stepping circuit as follows: from battery 407, conductor 408, relay 438, conductor 421, contact and armature of relay 418, conductor 411, and over the stepping circuit as before. Thus upon the next impulse, relay 438 is energized and completes a circuit for the cut-off relay 403 from battery 407 conductor 408, relay 438 and relay 403 in series, conductor 423, armature and contact of relay 438, sequence .switch contact 415 (1), sequence switch contact 326 (4) to ground. Relay 403 by its energization interrupts the fundamental circuit,-

right armature of relay 210 to ground. The

selector sequence switch thereupon moves to position 4. The energization of cut-ofi' relay 403 completed a. circuit from battery .424 through sequence switch motor magnet 400,

` sequence switch contact 425 (l), contact and left armature of relay 403 to ground. The sender sequence switch under control of its special contact 401 moves to position 3. When the sender sequence switch 400 moves from position 1 to position 3, it interrupted, at sequence switch contacts 415 and 419, the locking circuit for the counting relays which thereupon became denergized.

The selector sequence switch-25`1 in passing to position 4 completed a circuit from battery 227, through trip magnet 228, conductor 229, sequence switch contact 206 (4), conductor 207, and., sequence switch contact 208, to ground. When lthe brush carriage stops, after the brush 223 has passed over the irst two A interrupter segments, it is in such a position that the operation of the trip rod will place it in a position to release Y only the second set;l 21 of brushes upon the subsequent energization of the power magnet 220.

When the sender sequence switch 451 went into position 3, and the district sequence switch 251 into position 4, the fundamental circuit through the line relay 212 and the stepping relay 402 was yagain closed and both relays were again energized. The energization of the relay 212 completed a circuit from battery 202, through sequence switch motor magnet 200, conductor 203, sequence switch contact 204, conductor 216, sequence switchvcontact 217 (4), front contact and left armature` of relay 212, back contact and right armature of relay 210 to ground. The

selector sequence switch 251 thereupon passes to position 5. The selector sequence switch, inpassing into position 5, interrupted the circuit through line relay 212 at sequence switch contact 214, but substituted for thatportion of the circuit, a circuit through thev front contact and right armature of said relay, sequence switch contact 225 to sequence Contact 215, and ythen as before.

In position 5, the previously traced circuit for the selector power magnet 220 is again completed through the front contact and left armature of line relay 212, and when the brush carriage starts to move upward, the selected set 21 of brushes is released to a position to traverse the contacts in its section 231 of the terminaly bank. The B commutator is now connected in a branch from the fundamental circuit from ground, through brush 232, commutator B, conductor 233, upper sequence switch contact 215 (5) where it joins the fundamental circuit. Each section as 231 of the terminal bank will be composedv of a plurality of groups of terminals, the number of which and the number of terminals in a group being optional. The beginning of each group, however, will be indicated by the brush 232 passing over one of the segments of the B interrupter. Consequently, the group selected out of the section 231 will be dependent on the number ofv impulses required to effect the energization of the cut-off counting relay 403. The energization of stepping relay 402 completed a circuit from ground, through armature and contact of said relay, conductor 426, sequence switch contact 413 (3), conductor 427, top register contact 602 (2), conductor 439, relay 438, conductor 408 to battery 407 and ground. Relay 438 in pulling up completes a locking circuit from battery 407 conductor 408, relay 438, relay 403, conductor 423, armature and contact of relayy 438, sequence switch contact 415 (3), conductor 440, sequence switch contact 326 (4) to ground. Thus only one impulse will be necessary to cause the energization of cut-off relay 403.` The .cut-o" relay 403 now becomes ground. The district 'sequence switch thereupon passes to position 6. Theenergization of the cut-ofi1 relay 403 completed a circuit from battery 424, through sequence switch motor magnet 400, sequence switch contact 425 (3), conductor 428, contact and left armature of relay 403 to ground. The sender sequence switch thereupon moves to position 4. Line relay 212 again becomes energized over a circuit from battery 211, through the winding of 212, conductor 213, sequence switch contact 234 (6), conductor 235, fourth contact in the selected set, fourth brush of the cord finder, conductor 328, sequence switch 429 (4), to ground. f The energization of line relay 212 completes the previously traced 'circuit for' the sequence switch motor magnet 200 and the district sequence switch thereupon passes to position 7, thus completing a holding circuit for the line relay through itsfront contact and right armature, sequence switch contact 236 (7) conductor 237, to test brush 238. A branch from this circuit is also completed, extending from the right armature of relay 212 through sequence switch contact 225 (7),

conductor 239, interrupter C, and brush 240 to ground. The clutch magnet 220 of the switch becomes energized over the previously traced circuit, through sequence switch contact 222 (7) and the brushes start to hunt the terminals of an idle connecting circuit. All the busy terminals engaged by brush 238 will be connected to ground, thus retaining the relay 212 energized. While the ibrushes passing thereover and during the intervals while the brushes are passing between the terminals, the line relay will be held energized over the branch circuit through commutator C. When the test brush 238 becomes positioned centrally on an idle terminal without ground, the branch circuit through the commutator C is broken and the line relay 212 becomes denergized and interrupts the circuit for the. clutch" magnet 220, stopping the brushes on the terh minals of an idle trunk. A circuit is also completed from battery 202, through sequence switch motor magnet 200, sequence switch lcontact 226 (7), the back contact'and left armature of'relay 212, back contact and right armature of relay 210, to ground. The district ,or first selector sequence switch thereupon passes to position 8. The multiple terminals of the selected trunk are now caused /to test busy by la ground .from left armature and back contact of knock-down relay 210, conductor 272, sequence switch and sequence switch contact 429 (4) to ground. The energization of relay 212 eolnpleted the previously traced circult for the .sequence switch motor magnet 200 through sequence switch contact 204, conductor 216, uppersequence lswitch contact 217 (8), left armature and front contact of relay 212, and contact and armature of relay 210. The district sequence switch 200 thereupon passes to position 9.

When the operator pressed the oflice button, the office register took its position in a manner well understood, and as soon as the cord finder sequence switch reached position 4, a circuit was completed from battery 302 through cord finder sequence switch motor magnet 300, conductor 318, sequence switch contact 332 (4), conductor 333, sequence switch contact 430 (4), conductor 334, front contact and armature of cut-off relay 504, conductor 503, sequence switchy contact 321.(4), conductor 322 and ground at the actuated otlice key. The cord linder sequence switch 351 then moved to position 5 closing a circuit from battery 424, through sequence switch motor magnet 400, conductor 431, sequence switch contact 432 (4) and sequence switch contact 335 (5 to 16) to ground. The sender sequence switch 400 is moved to position 5. The reason for position 4 on the sender sequence switch is to assure that the office register has reached its set position before the sender sequence switch moves to position 5.

A fundamental circuit is now completed from the selected switch or second selector, over conductor 241 and the brush in association with its terminal contact to conductor 242, sequence switch contact 243 (9), conductor 244, middle-contact of the cord nder terminal set, middle cord finder brush, conductor 324, sequence switch `contact 325, (5),

stepping relay 402, right armature and back tact and armature of counting relay 410, conductor 441, upper register contact 603 (1), conductor 604, sequence switch contact '442 (5), conductor 426, contact and armature of relay 402 to ground. Relay 409Y is thereupon energized and attracts its armature, thus completing an energizing circuit in series therewith for relay 410, from battery 407, conductor 408, relays 409 and 410, armature and contact of relay 409, conductor 414, sequence switch contact 415 (5), sequence switch contact 326 (5) to ground.

y Relays 409 and 410 are locked up. Relay 410 by the attraction of its armature interrupted the stepping 'circuit leading to relay 409 and substituted for the relay 409 in the circuit just traced relay 417. When relay 402 is next energized, relay 417 is energized over the circuit just traced and in attracting its armature completes alocking circuit for relay 418 and itself in series from battery 407 conductor 408, relays 417 and 418, armay from battery 407, conductor 408, relay 438 and relay'403 in series, conductor 423, armature and contact of relay 438, sequence.

switch contact 415 (5), and sequence switch contact 326 (5) to ground. The relay 403 is energized and opens the fundamental circuit, bringing to a close lthe first cycle of operations at the second selector.

A circuitis now closed from battery 424, through sender sequence switch motor magnet 400, sequence switch contact 425 (5), conductor 428, contact and armature of relay 403 to ground, and the sender sequence switch moves from position 5 under the infiuence of its controlling contact 401 into position 7. 4 a

In passing from position 5 to position 7, the sequence switch interrupted at contacts 415 'and 419 the holding circuits for the counting relays. At position 7 the fundamental circuit vis again closed through to the second selector, again causing the energiza-l tion of the switch power magnet. Group selection at the second selector will now take place. As the switch shaft is elevated, curgization of stepping relay 402, a circuit is and complete a locking circuit for itself and' relay 403 in series through sequenceplswitch contact 415 (7) in a manner now understood. Relay 403 at the sender will beenergized to open the fundamental circuit, thus ending the second cycle of operations and stopping the brushes at the second selector at the bottom of the first group .of trunk terminals.

The brushes of the selected set at the second selector will now be caused to hunt for the terminals associated with an idle third selector.

Upon the energization of relay 403 a K circuit was completed from battery 424, through sequence switch motor magnet 400, conductor 443, oflice register contact 608 (l), district register contact 609 (2), conductor 444, sequence switch contact 433 (7 I conductor 428, contact and armature of relay 403 to ground. The sendersequence switch is moved toposition 8. The holding circuit for the counting relays is interrupted at contacts 415 and 419 as before.

While the sending operations just described, which occur rapidly and occupy an exceedingly short time, are taking place, the hundreds, tens and units registers will have reached their set positions and the cord finder sequence switch and the allotter will have undergone certain operations which ,will now be described. When the hundreds register reaches its set position, and its cut-oft' relay pulls up in a manner well understood, a circuit is completed from battery 302, sequence switch motor magnet 300, conductor 318, sequence switch contact 336 (5), conductor 337, front contact and right armature of cut-off relay 506, conductor 507, sequence switch contact 702 (1), conductor 508, actuated units key 521, conductor 509 and hundreds key 519 to ground.

The cord finder sequence switch now moves to position 6. When the tens register finds its proper position, a circuit is completed from battery 302, sequence switch motor magnet 300, conductor 318, sequence switch contact 336 (6), conductor 338, front contact and right armature of relay 510, con. ductor 507, and as before to ground through the actuated key of the hundreds set. The

cord nder sequence switch 351 now moves to position 7. Upon the units register reaching its set position, a circuit is completed from battery 302, motor magnet 300, conductor 318, sequence switch contact 332 (7), conductor 339, front contact and'left armature of relay 506, front contact and left armature of relay 510, front contact and armature of relay 511, conductor 507, to

ground as before through the actuated key of the hundreds set. -Motor magnet300 is thereupon energized and the sequence switch is carried from position 7` to position 9 by its special contact 301.

When the cord finder sequence switch entered position 8, ak circuit was completed from battery 703, through allotter motor magnet 700, conductor 340, sequence switch b contact 341 (8), sequence switch contact 704 (1) to ground. The allotter is thereupon moved from position 1 to position 3 under control of its special contact` 701. The al; vlutter in position 3 completes a circuit from battery 302, through the sequence switch motor magnet 300, conductor 318, sequence switch contact 342 (9), conductor 343, sequence switch contact 705 (3) to ground. The cord finder sequence switch 351 thereupon moves to position 10. A circuit is now completed from battery 424, through sequence switch motor magnet 400, conductor 431, sequence switch contact 432 (8), conductor 350, sequence switch Contact 344 (10) to ground. The sender sequence switch thereupon moves to position 9. This assures that the sender sequence switch will not go toposition 9 until the hundreds, tens and units registers have reached their set posi- 50 tions.

The sender sequence switch in passing out of position 8 interrupted at lower sequence switch contact 429 the circuit for the district line relay 212 and said relay fell back,

35 completing a circuit from battery 202 through motor magnet 200, sequence switch contact 226 (9), back contact and left armature of line relay 212, back contact and right .armature of relay 210 to ground. Sequence `switch 251 thereupon moves fromv position 9 to position 11. However, if the knockdown relay 210 had been actuated just at this instant, the sequence switch would have stopped in position 10 under the control of its special Contact 201.' The fundamental circuit is now closed to a third selector and the cycles of operations previously described in association with the second selector .will be repeated thereat. This fundamental circuit extends from ground and battery through the controlling relay at the third selector to one of the trunk conductors, thence back over a terminal contact of said trunk conductor and the second selector brush in engagement therewith, conductor 241 and the brush in engagement with its terminal contact, conductor 242, sequence switch contact 243, conductor 244, middle Contact of the cord nder terminal set, middle cord au finder brush, conductor 324, sequence switch contact 325, lstep relay 402, right armature and back contact of relay 403 and sequence switch contact 404, to ground. Upon the energization of relay1402, a circuit will be 55 completed from ground through armature messiey and contact of relay 402, conductor 426, sequence switch contact 447 (9), 'conductor 439, counting relay 438, conductor 408 and battery 407 to ground. Relay 438 is energized and completes a locking circuit for 704 itself and relay 403 in a manner Well understood. ln the circuits shown, which are adapted for a relatively Y small. exchange, the brush carriage would only take gne step,

the lfirst set of brushes being always tripped. s

When this system is adapted for a large exchange, the lower contact for a large switch spring 447 would not be joined directly to the wire 439 but would extend to a series of register contacts similar to those to which conductor,604 extends. When relay 403 becomes energized as al result of the energization of relay 438, the fundamental circuit will be interrupted, terminating the rst cycle of operations or brush selection at the 35 third selector.

Byothe energization of relay 403, a circuit is completed from battery 424 through sequence switch motor magnet 400, sequence' switch contact 425 (9), conductor 428, front 90 contact and left armature Vof relay 403 to ground. The sender sequence switch thereupon passes from position 9 to position 11 under control of its special contact 401. As the sequence switch passes through posiv tion 10, the holding circuits for the counting relays are interrupted as before.

When the sender sequence switch goes into position 11, the fundamental circuit is again closed through to the third selector. 10o This may cause the energization of the third selector switch power magnet and connect an interrupter similar to B, Fig. 1, in a shunt from the fundamental circuit. Group selection at the third selector now` takes place. .j

Upon energization of relay 402, a circuit will be completed from ground through armature and contact of relay 402, conductor 426, sequence switch contact 4-47 (11), conl110 ductor 448, sequence switch contact 358 (10), conductor 359, hundreds register contact 614 (4), conductor 439, relay 438, conductor 408, batteryV 407 to ground. Relay 438 will be energized and complete as before a locking circuit for 4itself and relay 403. Relay 403 lis energized and opens the fundamental circuit, thus terminating the second cycle of operations at the third selector. The brushes of the third selector will now automatically hunt for the terminals of a connecting circuit associated with an idle final connector.

.When relay 403 was energized it completed a circuit from battery 302, motor magnet 300, conductor 345, sequence switch contact 346 (10)', sequence switch contact 433 (11) front contact and left armature of relay 403 to ground. The cord nder sequence switch 351 is thereupon moved to posi-tion 12 under the control of its special contact 301. The fundamental circuit is again closed and brush selection takes place at the final connector.

Upon closing the fundamental circuit, a

circuit is closed from ground through armature and contact of relay 402, conductor 426,

sequence switch contact 447 (11), conductor 448, sequence switch conta'ct 358 (l2), conductor 360, hundreds register contact 612 (4), conductor 613relay 445, conductor 408,

I battery 407 to ground. Relay 445 is energized and completes a locking circuit for itself and the relay above it. 1n a manner well` understood. Each succeeding impulse through relay 402 serves to energize and lock up an additional pair of counting relays as before, until the relay 403 is energized and interrupts the fundamental circuit, terminating the brush selection operation at the final selector. Energization of relayv 403 completes a circuit from battery 30.2, sequence switch' motor magnet 300,

' ductor 345, sequence switch contact 346 (12),

Asequence switch contact 433 (11), conductor 42,8, contact4 and left armature of relay 403.

'conductor 362, tens register contact 615 (9),

conductor 616, relay 452 of the lastpair of counting relays to battery 407 and ground. Relay 452 is energized and completes a locki ing circuit for itself and the relay above it as before. -Upon each succeeding energization .of relay 402 an additional pair of counting relays is energized and locked up until relay 403 becomes energized and interrupts the fundamental circuit, thus selecting the tens group of terminals in which the v called subscribers line terminals are located. When relay 403 became energized,

-a circuit' was completed from battery 302, vsequence switch motor magnet 300, conductor'345, sequence switch contact 346 (12),.

sequence switch contact 433 (11), conductor 428, contact and left armature of relay 403 to ground. Sequence switch 351 thereupon movesrfrom position 14- to 16, lthus causing. the holding circuits for the counting relays to be interrupted at sequence switch contacts 326 and 314. The fundamental'circut is again closed and units Vselection now takes I' place. Upon the energizat'ion of relay 40,2

bythe closing of the fundamental circuit, a

circuit is closed from ground through armature and contact of relayz402, conductor 426, sequence switch contact-447 (11), conductor 448, sequence switch contact 361 (16), conductor 363, units register contact 617 (9) conductor 616, relay 452 to battery 407 an ground as before. The counting relays will be energized and locked up exactly as during tens selection, until relay 403 is energized. Relay 403 interrupts the funda-- mental circuit, thus determining the terminals on which the brushes of the final selector shall rest. The energization of the relay 403 completesaJ circuit from battery 424, through motor magnet 400, conductor 434, sequence switch contact y346 (16), sequence switchcontact 433 (11), conductor 428, contact and left armature of relay 403 to ground. The sender sequence switch 451 thereupon moves into position 12. In passing to position 12, a circuit is completed from battery 202, sequence switch motor magnet 200, conductor 203, lower sequence switchv contact 204 (11), conductor 245, f'

lower-most terminal in the contact set, lowermost brush of the cord finder, 'conductor 347, sequence "switch" contact 429 (12) ground. District sequence switch 251 is thereupon carried from position 11 to position 15 by its special contactv201. ,Sequence switch 251 in moving out of position 11 interrupted atsequence switch contact 209, a holding circuit for the test relay 309. Relay 309v is thereupon denergized and through its right armature completes a circuit from battery 302, sequence switch motor magnet 300, sequence switch contact 315 (16), back contact and right armature of relay309 to ground. Sequence switch 351 thereupon passes to Vposition 17. A circuit is now 'closedfrom battery 424, through sequence switch motor magnet 400, conductor 431, sequence switch contactl 435 (12), sequence switch contact 335 (17) to ground. The sender sequence switch451 thereupon returns from position 12 to its normal position under the control of its special contact l 401. As soon as the sender sequence switch 451 reaches position 13, a circuit is completed from battery 110, through listening key sequence switch motor magnet 100, sequence switch contact 111 (5), conductor 112, back contact and lef-t armature of listen-l ing out relay 348, sequence switch contact i 435 (13), sequence switch contact 335 (17) to ground. The listening key sequence switch 151 thereupon moves to position 8 under the control of Vits special contact 101, thus dsconnecting the operators telephone set from the line. As the listening key sequence switch moves through positions 6 and v7, a circuitis completed from battery 310, sequence switch 311 (17 right winding' of relay 348, continuity contacts 349, conductor 351, sequence switch contact 103 (6-7) to ground. Relay 348=pulls up and completes a locking circuit through its right armature,.and through its left armature completes a circuit from battery 302 through motor magnet 300, conduc tor 303, front contact and left armature of relay 348, sequence switch contact 435 (l), sequence switch contact 335 (17), to ground,

Cord finder sequence switch thereupon moves to position 18, where it will remain l until moved into position 1 by the allotter sequence switch contact 342.I (18), contact 705 (3) to ground. If the sequence-switch at cord inder Z be in position 9, this circuit would be momentarily held up. If both senders were busy, 436 and 436 would be both closed at their bottom contacts (2 toll) and the circuit would notbe completed until one or the other of the senders became idle. The busy condition of both senders is indicated by the glowing of lamp 449, its circuit being closed at contacts 436', 436, 1342', 342 and 705.

When the district sequence switch 251 entered position 2, the circuit for lamp 246 lwas closed at upper sequence switch contact 247 to the interrupter 248, and remained closed until the sequence switch'251 passed out of position 12. During this period the lamp 246 by its flashing indicates that the connection is being established. When the sequence switch passed out of position 12 a l closed circuit was established for the lamp 246 at lower sequence switch contact 247, this circuit being maintained closed in position 15 or the position at which the called subscriber is being rung. The steady glowing of lamp 246 indicates that the called subscriber is being rung. When the called subscriber removes his receiver from thehook, a circuit will be completed from battery 271 through relay 252, sequence switch contact 253 (l5-16), sequence switch contact 254 (15), right-brush of the irst selector over the line to the called subscriberns station, back over the other side of the line to the left brush of the first selector, through conductor 242, sequence switch contact 243 (l5-16) and back to battery. Relay 252 is thereupon energized and completes a circuit from battery 211 through line relay 212, front contact` and amature of relay 252 toj ground. Relay 212 is energized and completes a circuit from battery 202, ,sequence switch motor magnet 200, sequence switch.

contact 204, sequence switch contact 217 (15) front contact and left armature of relay 212,`

back contact and right armature of relay 210 to ground. Sequence switch 251 thereupon moves to position 16 or talking position. When relay 109 attracted its armature upon inserting plug 11vin pack 12, a circuit wasv completed from battery 255, through lamp 256, conductor 257, front contact and right armature of relay `109 to ground. Lamp 256, however, is shunted .through the armature of relay 258, the circuit of which extends contact 259 (1r to 4),. over the calling sub'- scribers line and sequencel switch Contact 260 (1 to- 4). When the listening key sequence switch goes to 5 or listening position, this circuit is interrupted and the armature of relay 258 will be retracted, lighting the lamp. Lamp 256 will continue to glow until the listening key sequence switch 151 passes out of position 5, when the circuit will be again completed from battery 271, through relay 258, sequence switch contact 259 (6 to 1), and sequence switch contact 260 (6 to 1),

kand the lamp will be extinguished and re` mains extinguished until the calling subscribed replaces his receiver on the hook, thus denergizing relay 258. y

-`When the called subscriber places his re` ceiver on the hook at the end of the conversation, the previously traced circuit through relay 252 is interrupted, and when it becomes denergized, it interrupts at its right armature the circuit for line relay 212, thus `completing a circuit for the signal lamp 261. This circuit may be traced from battery, through said lamp, sequence switch Contact 226 (16), back contact and .left armature of relay 212 and back Contact and left armature of relay 210, to ground. r1`he operator upon seeing lamp 261 or 256 glowing, will remove the plug 11 fromjack 12, causing relay 109 to become denergized, `and complete through its right armature a'circuit switch contact 274 (16, 17), left winding of knockdown relay 210, sequence switch cont-act 118 (8),n contact and armature of relay 109 to ground. Relay 210 is energized .and locks'over ai circuit through lower sefrom'battery l271 through sequence switch from battery 273, through top sequence' In position 18 a circuit is completed from` battery 263, through return clutch magnet 264, sequence switch contact 265 (18) to ground. The energization of magnet 264 retracts the holding pawl 267 and forces the switch lbar 24 ,into operative engagement with the return drive drum 28. lWhen the switch reaches its normal position, a circuit 'is completed from .ground through brushv 232, normal contact D, conductor 269, contact 204 (18), motor magnet 200, and battery 202 to ground. The district sequence switch 251'thereupon moves from position 102 (8) to ground through key 115.

18 back to position 1v or normal position.

)Vhcn relay 109 was denergized, it interrupted at its right armature the circuit for signal lamp 256, but a substitute path to ground is immediately closed at sequence switch contact 208 (18) thus lamp 256 lcontinues to glow until sequence switch 251 passes from position 18 to normal after all the apparatus associated with this cord circuit has returned to normal. v

If during the time of setting up a call the 'operator Ahad listened out on the particular call being established, either by connecting a cord circuit to al calling line or by operating the listening out key 114, a circuit would be completed from battery -110, through motor magnet 100, sequence switch contact 111 (5) to ground at key 114 or at sequence switch contact 111 (2 to 4), whereupon the listening key sequence switch 151 l would be moved to position 8, or nonlistening position, in which position it would remain until the denergization of relay 109, when the'plug 11 is moved from jack 12 at the end of conversation or until the listening in-key 115 is operated.

Should the operator at any .time wish to return to a connection from which her telephone has been disconnected, she may do so by pressing the listening in key 115, when a circuit will be completed from battery 110. sequence switch motor magnet 100, contct equence switch 151 will thus' be moved into position 1 vwhen a circuit will -be completed through contact 102 (1), front contact and left armature of relay 109 to ground, whereupon the. listening key sequence switch will be again moved to position 5 or listening-in position. 'v

Te will now consider the wipe-out operation. This can only occur when the selector sequence switch 251 is in positions 2 to 7, 9,

or 15 to 17 and when the listening key sequence switch isin position 5. Considering the operation with the selector sequence switch in position 2, we will assume that relay 309 has ,been energized andlocked up .Y

through its left armature. Thecord finder sequence switch 351 will now' be in position 3 and the sender sequence switch451 will be in position 1. The operation of the master wipe-out key 120 closes through its lower contact, a circuit from'battery 273, through sequence switch contact 274 (2), left winding of relay 210, sequence switch contact 118 (5), key l120 to ground. Relay 210 is energized and completes a circuit from battery 202, sequence switch motor magnet 200, conductor 203, sequence switch contact 204, conductor 262, sequence switch contact 205 to contact and left armature of relay 210 to ground. The selector sequence switch 251 v is thereupon carried through position 7to position 8 under the control of sequence' switch contact 205. In position 8 the'circuit is closed `from battery 263 through return clutch magnet 264, sequence switch contact 265 (8), contact and'left armature of relay 210 to ground. The brush carriage is thereupon returned to normal. When the carriage reaches its normal position, contact D is grounded through brush 232 and a circuit is completed from battery 202, sequence switch motor magnate 200, conductor 203, sequence switch contact 204 (8 to 18) conductor 269, contact D and brush-232 to ground. Sequence switch 251 is thereupon carried through position 18 to normal. The actuation of key 120 also closes ,a circuit from battery 310 through sequence switch contact 311 (3), right winding of relay 348, continuity contact 349, conductor 351 and key -120 to ground. Relay 348is energized and locks up through its right/armature.

When the knock-down relay 210 was ener-A gized, it interrupted at its back left contact the holding circuit for the test relay 309 whose armatures are retracted, and a circuit is completed from battery 302 through motormagnet 300, sequence switch contact 315 (3 to 16) and back contact and right armature of relay 309 to ground. Under the control of contact'315 (3 to 16), sequence switch 351 is carried to position 17. 'In position 17, a circuit is completed from battery 302, through m'otor magnet 300, conductor 303, front contact andleft armature of relay 348, sequence switch contact 435 (1), (the sender sequence switch being now in position 1), contact 335 (17) to ground. The cord iinder sequence switch thereupon moves to position 18 where itv stays until it is moved back to normal by the allotter. A

In positions 3 to 7 of the selector sequence switch, the wipe-out operation is substantially the same, except as tov the' sender. When sequence switch 251 is in positions 3 to 7, the sender sequence switch 451 will be in positions 2 to 12. Now when the cord L Y r f.

finder sequence switch goesto osition 17 as justA described; a circuit will e completed from battery 424, motor magnet 400, con-` ductor 431, sequence switch contact 435 (2 to 12), sequence switch contact 335 (17) to ground. Sequenceswitch 451 will thereupon be carried through position 12 under the control of contact 435 and will be returned to normal by its controlling contact'` before.

We will next assume that the master vwipeout key is actuated at the instant the selector sequence switch is leaving position 9, as we have previously stated that thev actuation of the wipe-out key at this instant would cause'sequence switch 351 to stop in posif tion 10. The knock-down relay'210 will be energized, sequence switch contact 274 being closed in position 10. The return magnet 263 is energized in position 10 over the previously traced circuit andthe brush carriage returns to normal. In normal position the circuit of the sequence switch motor magnet 200 is completed lthrough contact D and brush 232 as'before, and sequence switch 251 returns to normal. The rest of the restoration will' be substantially the same asV before described. f-

The wipe-out operation, when the selector sequence switch is in positions 16 or 17, will be similar to the operation just described and need not be further referred to.

Again referring to the features of the operators listening key structure and especially to the lfunction of the listening-out relay 348, from the foregoing it is; evident that when the operator for any reason actuates the wipe out key 120, and the switching and'sending apparatus is returned to normal, this relay by opening the circuit of the listening key sequence switch prevents disassociation of thev operators set from the cord. Also'that when she has set up a call to one subscriber through cord No. 1 and has removed her listening set to cord #2 b v inserting the plug of this cord in the jac of a second calling line, the listening key ysequence switch of cord #2 in passing through positions 6 and 7 closes at contact 103 the circuit of the relay 348, causing it to energize and lookup so that if the call over cord #l is disestablished while the operators set is still associated with cord #2, the circuit for the motor magnet of the listening key sequence switch of cord #2, through sequence switch contact 111 top, which would otherwise be completed through the left back contact. of 348 and sequence switch masia has vcontacts 435 andv 335- during restoration,

will be opened and the operators set will not be removed from\ cord #2 as would otherwise be the case.

What I claim is :4

1. In a telephone system, a plurality of y for interconnecting said lines, manually operable devices for uniting said cord circuits to said lines, a sending device for controlling said switches, a telephone set, means actuated upon the association of one of said connecting circuits with a line for uniting said telephone set thereto, and means associated with 'said sending device whereby when the connection reaches a predetermined stage, said telephone set is automatically removed from the circuit.

3. In a telephone, system, a plurality of telephone lines, connecting circuits for connection thereto, a telephone set common to said connecting circuits, a sequence switch for eachconnecting circuit, a controlling magnet for each switch, means whereby the controlling magnet of a sequence switch will be operated upon the association of a connecting circuit with a line to connect the telephone set to said circuit, and means whereby the magnet of said switch will be again actuated to remove said set fromsaid circuit when the connection being established reaches a predetermined stage.

4. In a telephone system, a plurality of telephone lines, connecting` circuits for connection thereto, a telephone set common to said connecting .circu1ts, switches, one for each connecting circuit for uniting Said telephone set thereto, an operating magnet for each of said switches, means whereby a magnet will be .energized upon the association of a connecting circuit with a line to causeits switch to connect the telephone set to said circuit, and means whereby said magnet will be again energized to cause its switch to remove said set from said circuit when the common to said connecting circuits, electro' magnbtic means associated with each connecting circuit for automatically uniting said telephone set thereto when said circuit is connected to a line, means for removing said telephoneI set from said circuit when the connection being established .thereover has reached a predetermined stage, and means whereby-said set will not be dsassociated from said circuit when a connection being established over fa second circuit reaches said predetermined stage.

6. In a telephone system, a plurality of lines, connecting circuits for association with said lines, a telephone set common to said connecting'circuits, electromagnetically operated'means individual to each connecting circuit for automatically uniting said telephone set thereto when said circuit is associated with a'line, a circuit common to said electromagnetically operated means, whereby said means will be actuated to remove said telephone set from a connecting circuit when the connection being established thereover reaches a predetermined stage, and means whereby said circuit will be rendered ineffective to cause the removal of lsaid telephone set from said circuit when a connection being established over another connecting `circuit reachesv said predetermined stage. 1'

7. In a telephone system, a pluralityl of lines, connecting circuits for association with said lines, a telephone set common to vsaid connecting circuits, electromagnetic means individual to each connecting circuit for automatically uniting said telephone set thereto when said circuit is associated with a line, a circuit having parallel" branches, each branch containing one of said electromagnets, whereby said electromagnetic means will be actuated to remove said telephone set from a connecting circuit when the connection being established thereover reaches a predetermined stage, and -means for altering said circuit whereby it will be rendered ineiiective to cause the removal of said telephone set from a connecting circuit when a connection being established over another circuit reaches said predetermined stage.v r

8. In-a'telephone system, a plurality of lines, connecting circuits for association withpsaid lines, a telephone set common to l said connecting circuits, electromagnetically operated means indivldual to each connectmg sociated with a line, a circuit common to said electromagnetically operated means, said circuit having parallel branches each containing one of said .electromagnets, whereby said means -will be actuated to re- .,rnove` said telephone set from a connecting circuit when the connectln being established thereover reaches a predetermined circuit for automatically uniting. said' telephone set thereto when said clrcuit 1s asstage, and a relay for interrupting said circult, whereby it will be rendered ineffective to cause the removal of'said set from a connecting circuit when the connectionbeing established over another connecting circuit reaches said predetermined stage. 9. In an automatic telephone system, subscribers lines, means comprlsing connecting' circuits and switches for establishing a connectlon between said lines, a lamp and means whereby said lamp will glow intermittently while said switches are being actuated, and will glow steadily from the time a connection is established until the called subscriber responds. .I

10. In an automatic telephone system, telephone lines, a group of connecting circuits, a plurality of controlling means for association with said circuits, means for associating one of said controllers with a.

connecting 'circuit upon uniting such-circuit to a line, and a signal for indicating when all of said plurality ofcontrollers are busy.

11. In an automatic telephone system, telephone lines, a group of connecting circuits, a plurality of controlling means for' association with. said connecting circuits, and a sequence switch for alternately associating said controllers with said connecting circuit upon uniting such circuits to calling lines, and a signal for indicating when all of said controllers are busy.

12. In an automatic telephone system, telephone lines, means operating in successive stages for establishing a connection between said lines, and a signal which by one another condition will indicate when the last switch has-functioned.

14. In an automatic telephone system, telephone lines, connecting circuits and switches for establishing connections between said lines, a controller for said switches, a plurality of switching devices, said controller being governed during part of a selecting operation by] one of said switching devices and during the rest of the selecting operation by another switching device, sald last mentioned switching device vbeing required at other times for other purposes. c I

1,5. In a telephone system, telephone lines, connecting. circuits and switches for establishing connections between said lines,a controller for said switches actuated by immesme pulses from said switches, a pair of sequence switches, said controller being governed during part of a selecting operation by one of said sequence switches and during the rest'of the selecting operation by the other sequence switch, said last mentioned sequence switch being required at other times for other purposes.

16.ln a telephone system, a plurality ot telephone lines, cord circuits, means for connecting said cord circuits to said lines, mechanical switches for extending said cord circuits to a called subscribers line, a telephone set, a'switching device operated upon joining a cord circuit to a line for uniting said telephone set thereto, and means for again actuating said device when the nal switch engages the contacts of a called line to remove said set from said cord circuit.

17. In a telephone system, a plurality of lsubscribers lines, cord circuits, switches for extendinga cord clrcult to calling and called subscribers line for joining the telephone set thereto, and means automatically actu# ated when said sending device has reached a predetermined stage in its operation for removing said telephone set from said line.

In witness whereof, I hereunto subscribe my name this 18th day of August, A.. D.

ALBEN E. LUNDELL. 

